The US Army has 20 divisions in its regular establishment, half of which is National Guard. These days nearly all of this force is at home.
I am speaking here of combat maneuver units, not including supporting arms, which are usually assigned proportionally.
There is about one division-equivalent in Europe right now, and a brigade (1/3 of a division) in South Korea.
There are a disproportionate number of supporting arms (artillery, helicopters, etc.) and service personnel in South Korea however. There are also support and logistics units in other countries, like Japan.
So, out of the whole establishment of the combat units of the US Army, @ 92% are in the US.
As for equipment, there is a considerable amount prepositioned in various places abroad. What and where is not disclosed AFAIK. Much of it is in Europe (Germany, and Poland, probably) South Korea, and the Middle East or Diego Garcia, probably.
Whats been sent to Ukraine or is likely to be is a tiny proportion of US equipment holdings. Much more is on its way to Poland, proportionately - as a proxy for total arms transfers, 350 out of the 6000+ M1 Abrams tanks as of 2022 are in or on their way to Polish service.
Compare to the Cold War days.
Advice - do not be fooled by the buzz. Look for the details on your own.
We are not transferring US tanks to Poland - they are getting them new - an export version, M1A2M, which has no classified anything on it - they can stick their own stuff on it. They are currently in production and the first deliveries will be by the end of the year.